Further studies will be carried out on oxygen-dependent killing mechanisms of neutrophils. The respiratory burst oxidase from stimulated neutrophils will be purified and characterized, paying particular attention to the role of cytochrome b558 in its activity. Cloning of the gene for the 67K component of the oxidase will be initiated using probes prepared from peptide sequences determined on the purified material. Antibodies will be raised to the oxidase and used for studying the structure of the enzyme, its ontogeny and its occurrence in other cells. Studies will also be continued on the mechanisms of mutagenesis in bacteria that have been exposed to activated neutrophils.